Two-voltage battery

ABSTRACT

A two-voltage battery for a vehicle, having an earth point, having a plurality of battery cells, wherein groups of battery cells connected in series form battery cell blocks, and wherein at least one first battery cell block is preferably permanently connected to the earth point of the two-voltage battery, having a plurality of cell monitors for the battery cell blocks, wherein the cell monitors are designed to monitor a voltage provided by the individual battery cells in the particular battery cell block and/or a current through the battery cells in the particular battery cell block, and having a plurality of power switching elements for selectively connecting the battery cell blocks in parallel and/or in series.

This nonprovisional application is a continuation of InternationalApplication No. PCT/EP2018/053559, which was filed on Feb. 13, 2018, andwhich claims priority to German Patent Application No. 10 2017 103869.8, which was filed in Germany on Feb. 24, 2017, and which are bothherein incorporated by reference.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to a two-voltage battery for a vehicle,having a ground point, having a multiplicity of battery cells, whereingroups of series-connected battery cells form battery cell blocks andwherein preferably at least one first battery cell block is permanentlyconnected to the ground point of the two-voltage battery, having amultiplicity of cell monitors for the battery cell blocks, wherein thecell monitors are designed to monitor a voltage provided by theindividual battery cells of the relevant battery cell block and/or acurrent through the individual battery cells of the relevant batterycell block, and having a multiplicity of power switching elements forconnecting the battery cell blocks in parallel and/or in series asdesired, wherein, in a first connection arrangement the battery cellblocks are connected in parallel and a first voltage is provided at afirst terminal, and wherein, in a second connection arrangement thebattery cell blocks are connected in a series arrangement and the firstvoltage is provided at the first terminal and/or a second voltage isprovided at a second terminal.

Description of the Background Art

Known from DE 10 2013 113 182 A1 is a two-voltage battery having amultiplicity of battery cell blocks, which in a first connectionarrangement provides a first voltage at a first terminal for supplying afirst group of electrical loads, and in which a second connectionarrangement provides a second voltage at a second terminal for supplyinga second group of electrical loads. Bringing the battery cell blocksinto the first connection arrangement and/or into the second connectionarrangement is accomplished by means of a group of power switchingelements. As a function of the switching state of the power switchingelements, the battery cell blocks of the generic two-voltage battery areconnected in parallel or in series with one another. For example, thetwo-voltage battery is used to supply power in a 12 V vehicle electricalsystem and in a 48 V vehicle electrical system in a single vehicle. Thetwo voltages can be made available by the two-voltage battery, inparticular simultaneously, through the two different terminals.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide a cellmonitor arrangement for the two-voltage battery that makes it equallypossible in the different connection arrangements to monitor a voltagesupplied by the battery cell blocks or a current through the batterycell blocks, and to centrally provide information in this regard.

In an exemplary embodiment, the cell monitors can be connected through adata line arrangement to a microcontroller of the two-voltage battery,wherein a voltage level adapter is provided between at least individualcell monitors and the microcontroller, which voltage level adapterprovides, in the first connection arrangement and in the secondconnection arrangement of the battery cell blocks, at an outputconnected directly or indirectly to the microcontroller, an outputvoltage signal that is in a prespecified voltage level interval for aninput voltage signal that is present at an input of the voltage leveladapter associated with the associated cell monitor and has a differentvoltage level in the first connection arrangement and in the secondconnection arrangement, the interval width of said voltage levelinterval being smaller than a difference between the voltage level ofthe input voltage signal in the first connection arrangement and in thesecond connection arrangement.

The provision of the voltage level adapter makes it possible for thecell monitors to measure the voltage of the individual battery cells ofthe relevant battery cell block or the current through the battery cellsin both the first connection arrangement and the second connectionarrangement. In this context, the measurement is independent of avoltage level of the battery cell blocks, which differs at least forindividual battery cell blocks for parallel and serial connection of thebattery cell blocks. While a voltage that is always equal and low, inparticular the first voltage, is always present across the differentbattery cell blocks during a parallel connection of the battery cellblocks, the voltage of the series-connected battery cell blocks isadditive, with the result that a higher voltage, in particular thesecond voltage, is provided overall. Accordingly, the different batterycell blocks are at a different voltage level in the series arrangement.Consequently, regardless of a voltage level of the associated batterycell block, the cell monitors provided for monitoring the battery cellblocks must always permit reliable monitoring in conjunction with themicrocontroller and provide information about this to the centralmicrocontroller of the two-voltage battery.

The voltage level adapter is designed to convert the input voltagesignal provided by the cell monitor and to make available at the outputan output voltage signal that can be made available indirectly ordirectly to the microcontroller and can be read in and interpreted oranalyzed by the latter. A direct analysis of the output voltage signalby the microcontroller occurs when the voltage level adapter isconnected directly to the microcontroller. An indirect analysis providesthat additional components, for example another voltage level adapter oranother cell monitor, are interposed. The voltage level interval for theoutput voltage signal is chosen here such that a distinction can be madeon the part of the microcontroller between a logical zero on the onehand and a logical one on the other hand. For example, a voltage signalin the range from 0 V to 0.6 V is interpreted as a logical zero and avoltage level of more than 0.6 V to approximately 5 V is interpreted asa logical one.

For example, a cell monitor can be associated with each battery cellblock, and a voltage level adapter can be associated with each cellmonitor. It is ensured by this means that signals from each cell monitorare converted and, in particular, are handled uniformly. For example, apropagation delay change can occur due to the provision of the voltagelevel adapter, and the uniform handling of the signals can be achieveddue to the provision of a voltage level adapter for every cell monitor.In particular, a reversal of a sequence of the signals upon reception bythe microcontroller is prevented.

A voltage level adapter can be provided for every cell monitor that isassociated with a battery cell block that is not permanently connectedto the ground point of the two-voltage battery. An especially economicalsolution advantageously results in this way, because the number ofvoltage level adapters remains small and a voltage level adapter can beomitted for the battery cell blocks or the cell monitors associated withthem that have an equal voltage level in the first connectionarrangement and in the second connection arrangement or are connected tothe ground point of the two-voltage battery.

The cell monitor of the first battery cell block can be capacitively orgalvanically connected to the microcontroller through the data linearrangement. The capacitive or galvanic connection can be providedbecause the first battery cell block of the two-voltage battery isprovided at an equal voltage level in the first connection arrangementand in the second connection arrangement.

The data line arrangement can be designed in the manner of a network.Then bus data lines, for example, are provided for communication of themicrocontroller with the cell monitors. Alternatively, the data linearrangement can provide a first line routed to the microcontroller and asecond line routed to the microcontroller, wherein a voltage differenceis delivered to the microcontroller through the first line and thesecond line, and the output voltage signal or information about a stateof the battery cell blocks is determined from the voltage difference.

The microcontroller can be associated uniquely with the two-voltagebattery. The microcontroller can be arranged inside a housing of thetwo-voltage battery or outside the same.

A transmitter with inductive decoupling can be provided as a voltagelevel adapter, wherein the transmitter provides a microcontrollerwinding that is connected to the microcontroller and a cell monitorwinding that is connected to the cell monitor. The transmitter can bedesigned as a transformer.

A common transmitter can be associated with a multiplicity of cellmonitors. The common transmitter has a multiplicity of cell monitorwindings, wherein each cell monitor interacts with at least one cellmonitor winding of the common transmitter. In addition, one commonmicrocontroller winding is provided for at least two and preferably forall cell monitor windings of the transmitter. The common transmitter andthe common microcontroller winding advantageously bring about a compactconstruction and, as a result, a small space requirement and/or a costadvantage.

A level converter circuit with galvanic coupling can be provided as avoltage level adapter. The level converter circuit is arranged betweentwo battery cell blocks that are next to one another in the secondconnection arrangement. The provision of galvanic coupling by means of alevel converter circuit is advantageously associated with comparativelylow costs.

The level converter circuit can provide a first circuit path for signaltransmission from the cell monitor to the microcontroller and a secondcircuit path for signal transmission from the microcontroller to thecell monitor. By this means, a separate adjustment of the voltage levelfor signal transmission in the two circuit paths is advantageously madepossible.

The level converter circuit can be designed as an integrated circuit.For example, the level converter circuit can be implemented as part ofthe associated cell monitors and, in particular, be integrated spatiallyinto the cell monitors. A discrete construction of the level convertercircuit and/or a spatially separate embodiment of the same are equallypossible according to the invention.

More than two battery cell blocks can be connected in series with oneanother in the second connection arrangement. A voltage level adapter isalways provided here between every two adjacent battery cell blocks inthe second connection arrangement. Preferably, all voltage leveladapters are identical in design. A cost advantage results fromproviding the identical design of voltage level adapters. Moreover, theregular arrangement of the voltage level adapters is advantageous. Itsimplifies communication through the data line arrangement as well asinstallation or assembly.

The transmission of the signals to the microcontroller or thetransmission of the signals from the microcontroller to the cellmonitors can take place in a cascading manner such that only the firstbattery cell block interacts directly with the microcontroller throughthe data line arrangement, and all other battery cell blocks or the cellmonitors associated with them communicate with the microcontrollerthrough the first battery cell block. The additional battery cell blocksinteract only indirectly with the microcontroller in this regard or areonly indirectly connected to the microcontroller.

A first switching module with at least one switching element, with aswitching input associated with the switching element, and with a signaloutput is provided in the first voltage path of the level convertercircuit. The at least one switching element is arranged in a firstswitching state or in a second switching state depending on an inputswitching signal present at the switching input of the switchingelement. In the different switching states of the switching element, aresistor or multiple resistors of the first switching module is or areconnected differently in such a manner that the voltage level at thesignal output of the first switching module in the first switching stateof the switching element is different from the voltage level of thesignal output in the second switching state with respect to an equaldifferential voltage at two voltage terminals of the first switchingmodule. Analogously, a second switching module, likewise with at leastone switching element, with a switching input associated with theswitching element, and with a signal output can be provided in thesecond voltage path of the level converter circuit. The switchingelement of the second switching module is arranged in a first switchingstate or in a second switching state depending on an input switchingsignal present at the switching input of the switching element, and aresistor or multiple resistors of the second switching module areconnected differently as a function of the switching state such that thevoltage level at the signal output of the second switching modulediffers—with respect to an equal differential voltage at two voltageterminals of the second switching module—as a function of the switchingstate of the switching element. Advantageously, the adaptation of thevoltage level can take place in a customized and need-based manner dueto the provision of the first switching module and/or the secondswitching module for the different voltage paths of the level convertercircuit. Possibilities for switching elements include, for example,transistors or digital transistors, MOSFET, or other controllablesemiconductor elements.

Further scope of applicability of the present invention will becomeapparent from the detailed description given hereinafter. However, itshould be understood that the detailed description and specificexamples, while indicating preferred embodiments of the invention, aregiven by way of illustration only, since various changes, combinations,and modifications within the spirit and scope of the invention willbecome apparent to those skilled in the art from this detaileddescription.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from thedetailed description given hereinbelow and the accompanying drawingswhich are given by way of illustration only, and thus, are not limitiveof the present invention, and wherein:

FIG. 1 is a schematic diagram of a two-voltage battery according to theinvention with a multiplicity of battery cell blocks that can beconnected to one another in a first connection arrangement or in asecond connection arrangement,

FIG. 2 is a first circuit configuration for a multiplicity of cellmonitors of the two-voltage battery associated with the battery cellblocks in the second connection arrangement,

FIG. 3 is a second circuit configuration for the cell monitors of thetwo-voltage battery from FIG. 1 in the second connection arrangement,

FIG. 4 is a detailed representation of a switching module Z of thecircuit arrangement from FIG. 3,

FIG. 5 is a detailed representation of a switching module Y of thecircuit arrangement from FIG. 3, and

FIG. 6 shows the circuit configuration of the cell monitors of thetwo-voltage battery from FIG. 3 in the first connection arrangement.

DETAILED DESCRIPTION

A two-voltage battery 1 according to FIG. 1 includes a total of eightbattery cell blocks A1, A2, A3, C, D, each of which is formed of amultiplicity of series-connected battery cells that are not depictedindividually. Of the total of eight battery cell blocks A1, A2, A3, C,D, a first battery cell block A1, a second battery cell block A2, and athird battery cell block A3 form a first group 2 of battery cell blocksA1, A2, A3. Connected in parallel with the first group 2 of battery cellblocks A1, A2, A3 are two fourth battery cell blocks C, D and a secondgroup 3, which is shown as hidden in the schematic circuit diagram inFIG. 1, having three additional battery cell blocks that are notdepicted individually.

As power switching elements, parallel connection switches P1+, P2+, P2−,P3+, P3− and series connection switches S1, S2, S3 are associated withthe battery cell blocks A1, A2, A3, C, D. The association of the powerswitching elements P1+, P2+, P2−, P3+, P3−, S1, S2, S3 with the batterycell blocks A1, A2, A3, C, D takes place in such a manner that, in afirst connection arrangement of the two-voltage battery 1, all batterycell blocks A1, A2, A3, C, D are connected in parallel with one another.Thus, the first battery cell block A1, the second battery cell block A2,and the third battery cell block A3 of the first group 2 of battery cellblocks A1, A2, A3 are in parallel with one another. Moreover, thebattery cell blocks of the second group 3 of battery cell blocks are inparallel with one another and are also in parallel with the battery cellblocks A1, A2, A3 of the first group 2 of battery cell blocks A1, A2,A3. The two groups 2, 3 of battery cell blocks A1, A2, A3 are againconnected in parallel with the fourth battery cell blocks C, D. In thefirst connection arrangement, a first voltage is provided at a firstterminal 4 of the two-voltage battery 1.

In the second connection arrangement, the first battery cell block A1,the second battery cell block A2, and the third battery cell block A3 ofthe first group 2 of battery cell blocks A1, A2, A3 are series-connectedor connected in series with one another. The battery cell blocks of thesecond group 3 of battery cell blocks are likewise connected in serieswith one another. In the second connection arrangement, a second voltageis provided at a second terminal 5 of the two-voltage battery 1. Thesecond voltage is higher than the first voltage on account of the seriesarrangement of the battery cell blocks A1, A2, A3.

Optionally, in the second connection arrangement, the first voltage canbe provided at the first terminal 4 in addition. Serving to provide thefirst voltage are the two fourth battery cell blocks C, D and optionallyalso the first battery cell block A1 of the first group 2 of batterycell blocks A1, A2, A3 in addition to a corresponding first battery cellblock of the second group 3 of battery cell blocks.

For example, with respect to a ground point 11, the two-voltage battery1 provides a first voltage of 12 V at the first terminal 4 and/or asecond voltage of effectively 48 V (nominally 36 V) at the secondterminal 5. A starter-generator 6 is optionally associated with thetwo-voltage battery 1. The starter-generator 6 can be connected asdesired through a first power switching element 7 at the first voltageand/or through a second power switching element 8 at the second voltage.The starter-generator 6 can be operated by the two-voltage battery 1 orcan be used in generator mode to convert braking energy into electricalenergy and feed it into the two-voltage battery 1.

At least one first electrical load 9 that is operated at the firstvoltage is connected to the first terminal 4 of the two-voltage battery1. At least one second electrical load 10 can be connected in analogousfashion to the second terminal 5 of the two-voltage battery 1. Thesecond electrical load 10 is operated at the second voltage.

According to the invention, cell monitors Z1, Z2, Z3 for monitoring thebattery cell blocks are associated with the various battery cell blocksA1, A2, A3, C, D of the two-voltage battery 1.

FIG. 2 shows the battery cell blocks A1, A2, A3 of the first group 2 ofbattery cell blocks A1, A2, A3 in the second connection arrangement, inwhich the battery cell blocks A1, A2, A3 are connected in series to oneanother. Likewise shown are the cell monitors Z1, Z2, Z3 associated withthe battery cell blocks A1, A2, A3 and also a microcontroller 12 of thetwo-voltage battery 1. The microcontroller 12 is connected to the cellmonitors Z1, Z2, Z3 by a data line arrangement 13. Furthermore,transformers 14, 15, 16 as voltage level adapters or transmitters withinductive decoupling are provided between the cell monitors Z1, Z2, Z3on the one hand and the microcontroller 12 on the other hand. Thetransformers 14, 15, 16 each have a cell monitor winding associated withthe cell monitors Z1, Z2, Z3 and a microcontroller winding thatinteracts with the cell monitor winding and is associated with themicrocontroller 12. Associated on the microcontroller side with thetransformers 14, 15, 16 are a first line 17 and a second line 18, whichare routed to the microcontroller 12 and are designed as part of thedata line arrangement 13.

The cell monitors Z1, Z2, Z3 are designed to monitor a voltage providedby individual battery cells of the associated battery cell block A1, A2,A3 or a current through the battery cells of the relevant battery cellblock A1, A2, A3. The cell monitors Z1, Z2, Z3 transmit the informationabout the voltage or the current to the microcontroller 12, which inthis regard has the information on hand about proper functioning or afault of the battery cell blocks A1, A2, A3. It is the case here that anoutput signal from the cell monitors Z1, Z2, Z3 arrives at thetransformers 14, 15, 16 serving as voltage level adapters. The signal ofthe cell monitors Z1, Z2, Z3 will be present there as an input voltagesignal and be converted according to the winding configuration into anoutput voltage signal that lies in a predefined voltage level interval.The output voltage signal arrives at the microcontroller 12 over thedata line arrangement 13 with the first line 17 and the second line 18.The microcontroller 12 analyzes a voltage difference between the lines17, 18.

In the series arrangement of the battery cell blocks A1, A2, A3 fromFIG. 2, the first battery cell block A1 is connected to ground. Itprovides a nominal voltage of 12 V, which serves as a base voltage forthe second battery cell block A2. The second battery cell block A2 inturn provides a nominal 12 V voltage, so that the third battery cellblock A3 is at 24 V and in turn provides a nominal 12 V. Consequently, a36 V voltage (effectively: 48 V) is nominally present across the firstgroup of battery cell blocks A1, A2, A3. While a signal voltage between0 V and 5 V is provided on the part of the cell monitor Z1 associatedwith the first battery cell block A1 as the input voltage signal for theassociated transformer 14, a voltage that is higher by an offset of 12V, namely 12 V to 17 V, is present as the input voltage signal for thetransformer 15 of the cell monitor Z2 associated with the second batterycell block A2. In an analogous manner, 24 V to 29 V are present at thetransformer 16 of the cell monitor Z3 associated with the third batterycell block A3. Now, the transformers 14, 15, 16 are designed such thatin each case an output voltage signal of 0 V to 5 V is provided at themicrocontroller winding as the input signal for the microcontroller 12.For example, a voltage in the range from 0 V to 0.6 V can be interpretedby the microcontroller 12 as a logical zero and as an indication ofincorrect functioning of a battery cell block A1, A2, A3, and an inputvoltage in the range of 0.6 V or more as a logical one and as anindication of proper functioning of the battery cell blocks A1, A2, A3.

According to an alternative embodiment of the invention shown in FIGS. 3to 6, a level converter circuit 19 is provided as voltage level adapterthat serves together with the data line arrangement 13 to connect thecell monitors Z1, Z2, Z3 to the microcontroller 12. The communication ofthe cell monitors Z1, Z2, Z3 with the microcontroller 12 is galvanicallycoupled in this regard.

In the series arrangement of the battery cell blocks A1, A2, A3 of thefirst group 2 of battery cell blocks A1, A2, A3 in FIG. 3, one levelconverter circuit 19 apiece is provided between the first battery cellblock A1 and the second battery cell block A2 on the one hand, andbetween the second battery cell block A2 and the third battery cellblock A3 on the other hand. Moreover, a data bus line 20 to themicrocontroller 12 is provided from the first battery cell block A1,which is permanently connected to the ground point 11 of the two-voltagebattery 1. The signal transmission between the microcontroller 12 on theone hand and the cell monitors Z1, Z2, Z3 on the other hand takes placeover two separate circuit paths in this design. A first circuit pathserves for signal transmission from the cell monitor Z1, Z2, Z3 to themicrocontroller 12, and a second circuit path serves for signaltransmission from the microcontroller 12 to the cell monitors Z1, Z2,Z3. The level converter circuit 19 can be implemented discretely or canbe composed of an integrated circuit that is, e.g., also integratedspatially into the cell monitors Z1, Z2, Z3 themselves.

In the first voltage path of the level converter circuit 19, twostructurally identical first switching modules Z are provided forcommunication from the cell monitor Z1, Z2, Z3 to the microcontroller12. The first switching module Z is shown in detail in FIG. 4. Itincludes a switching element 21, which preferably is implemented as atransistor or digital transistor, a switching input 22 associated withthe switching element 21, and a signal output 23. Moreover, two voltageterminals 24, 25 are provided on the first switching module Z.

The second voltage path, through which the signal transmission from themicrocontroller 12 to the cell monitors Z1, Z2, Z3 takes place, providestwo structurally identical second switching modules Y. A secondswitching module Y is shown in detail in FIG. 5. The second switchingmodule Y provides two switching elements 26, 27 with a switching input28, 29 associated with each of the switching elements 26, 27. Moreover,a signal output 30 is provided. In addition, two voltage terminals 31,32 are formed for the second switching module Y.

For the series-connection of the battery cell blocks A1, A2, A3 in FIG.3, the voltage difference across the voltage terminals 24, 25 of thefirst switching module Z or across the voltage terminals 31, 32 of thesecond switching module Y is nominally 24 V in each case for the firstvoltage path (signal transmission from the cell monitor Z1, Z2, Z3 tothe microcontroller 12). A voltage difference of 12 V is present acrossthe cell monitors Z1, Z2, Z3 in each case, wherein the first cellmonitor Z1 associated with the first battery cell block A1 operatesnominally between 0 V and 12 V, the second cell monitor Z2 associatedwith the second battery cell block A2 operates nominally between 12 Vand 24 V, and the third cell monitor Z3 associated with the thirdbattery cell block A3 operates nominally between 24 V and 36 V.

Using the example of the level converter circuit 19 between the secondbattery cell block A2 and the first battery cell block A1, the operatingprinciple of the voltage level adapter in the serial arrangement isexplained separately for the first circuit path and the second circuitpath by way of example below. It is assumed here that the ports for thecommunication of each cell monitor Z1, Z2, Z3 are designed for a voltagerange of 0 V to 5 V relative to the lower supply voltage. Accordingly,the signal for the first signal path in the case of the second cellmonitor Z2 can be 12 V or 17 V—depending on the bit to be transmitted atthe time. For the output signal, the voltage level interval from 0 V to5 V must be transmitted so that it can be analyzed by means of themicrocontroller 12 or the first cell monitor Z1. Analogously, amicrocontroller signal in the range from 0 V to 5 V is converted throughthe second circuit path into a signal for the second cell monitor Z2 inthe range from 12 V to 17 V.

The signal coming from the second cell monitor Z2 is in the region of 12V or 17 V. It is associated with the first switching module Z throughthe switching input 22, wherein the switching element 21 of the firstswitching module Z is implemented as a PNP transistor, which is switchedto conduct in the event of an incoming logical zero. Since a voltagedifference of 24 V is present across the voltage terminals 24, 25 in theseries arrangement (second connection arrangement), a signal of 5 V canbe tapped through the voltage divider for two resistors 33, 34 when thetransistor 21 is conducting. If the transistor 21 is not conducting, 0 Vis present at the signal output 23. It should be noted here that in thecase of a logical one at the switching input 22, the switching element21 blocks, and thus a logical zero (0 V) is present at the signal output23. In the case of a logical zero at the switching input 22, thetransistor 21 conducts, and thus a logical one is present at the signaloutput 23. Thus, the switching module Z has an inverting characteristic.

For the second circuit path, the second switching element 27 of thesecond switching module Y is designed to block in the serialconfiguration. A logical zero is continuously present at the secondswitching input 29 in this regard. In the serial configuration, only thefirst switching input 28 of the second switching module Y is used forswitching or transmission. In the case of a logical zero at theswitching input 28 of the first switching element 26, the firstswitching element 26 blocks. A voltage is then present at the signaloutput 30 that results solely from the voltage divider formed by theresistors 35, 36, 37, taking into account the voltage across the voltageterminals 31, 32. In the case of a logical one at the switching input28, the switching element 26 conducts and the voltage at the signaloutput 30 is defined by the voltage divider formed by the resistors 36,37, 38 and by the non-switchable resistor 35 connected in parallel. Theresistors 35, 36, 37, 38 are selected in this case such that an outputvoltage of approximately 17 V is established when the switching element26 blocks, and an output voltage close to 12 V is established when theswitching element conducts.

A configuration of the level converter circuit 19 that is providedbetween the third battery cell block A3 and the second battery cellblock A2 is selected in an analogous fashion. The circuit paths and thefirst switching module Z and the second switching module Y are of thesame design. Operation and signal transmission take place in the samemanner based on the premise that, in the series circuit arrangement fromFIG. 3, the voltage level for the second cell monitor is nominally 12 Vto 24 V and for the third cell monitor is nominally 24 V and 36 V, andthat nominally 12 V to 36 V, which is to say a voltage difference of 24V, is present across the voltage terminals 24, 25, 31, 32. The switchinginputs 22, 28, 29 and the signal outputs 23, 30 of the switching modulesZ, Y are each above the above-discussed configuration by 12 V.

A signal transmission from the microcontroller 12 to the first batterycell block A1 takes place solely through the bus data line 20. A signaltransmitted from the microcontroller 12 to the second battery cell blockA2 is transmitted through the first battery cell block A1 and from therethrough the first switching module Z of the level converter circuit 19to the second battery cell block A2. A signal transmission from themicrocontroller 12 to the third battery cell block A3 takes placethrough the first battery cell block A1, the first switching module Z,the second battery cell block A2, and the additional first switchingmodule Z to the third battery cell block A3.

In analogous fashion, transmission of the signal from the battery cellblocks A1, A2, A3 to the microcontroller 12 takes place in a cascadingmanner such that a signal from the third battery cell block A3 istransmitted through the second switching module Y to the second batterycell block A2, and from there through the additional second switchingmodule Y to the first battery cell block A1. From the second batterycell block A2, the signal is transmitted through the second switchingmodule Y to the first battery cell block A1, and from there to themicrocontroller 12. Transmission from the first battery cell block A1 tothe microcontroller 12 takes place over the data bus line 20.

In the parallel configuration of the battery cell blocks A1, A2, A3 ofthe first group 2 of battery cell blocks A1, A2, A3 from FIG. 6, allcell monitors Z1, Z2, Z3 and the switching modules Z, Y are at a voltagedifference of 12 V between 0 V and 12 V. The method of operation of thefirst switching module Z in this case is analogous to the descriptionabove. However, a voltage of 0 V or approximately 2.5 V is present atthe signal output 23. The difference in the voltage level is greatenough, however, that a logical zero and logical one can bedistinguished not only by an input port of the cell monitor Z1, Z2, Z3but also by the microcontroller 12.

For the second switching module Y in the parallel configuration, thefirst switching element 26 is continuously switched to conduct and thesecond switching element 27 is actuated. In the case of a logical zeroat the second switching input 29, the second switching element 27blocks, and the voltage drop across the resistor 39 has no effect on thesignal output 30. In contrast, when the second switching element 27conducts in the case of a logical one at the input 29, the resistor 39contributes to determining the signal output 30. The resistors 35, 36,37, 38 on the one hand, and also the resistor 39, which is relevant onlyin the parallel configuration, are selected such that an output voltageof nominally 5 V is established in the event of a blocking transistor27, and an output voltage of nominally 0 V is established in the eventof a conducting transistor 27. The second switching module Y likewisehas an inverting characteristic here. A logical one at the input 29 ofthe transistor results in a logical zero at the output 30, and a logicalzero at the input 29 results in a logical one at the output 30.

The same components and component functions are labeled with the samereference symbols.

The invention being thus described, it will be obvious that the same maybe varied in many ways. Such variations are not to be regarded as adeparture from the spirit and scope of the invention, and all suchmodifications as would be obvious to one skilled in the art are to beincluded within the scope of the following claims.

What is claimed is:
 1. A two-voltage battery for a vehicle, comprising:a ground point; a plurality of battery cells, wherein groups ofseries-connected battery cells form battery cell blocks and at least onefirst battery cell block is permanently connected to the ground point ofthe two-voltage battery; a plurality of cell monitors for the batterycell blocks, the cell monitors monitor a voltage provided by theindividual battery cells of the relevant battery cell block and/or acurrent through the battery cells of the relevant battery cell block;and a plurality of power switching elements to connect the battery cellblocks in parallel and/or in series, wherein, in a first connectionarrangement the battery cell blocks are connected in parallel and afirst voltage is provided at a first terminal, and wherein, in a secondconnection arrangement the battery cell blocks are connected in a seriesarrangement and the first voltage is provided at the first terminaland/or a second voltage is provided at a second terminal, wherein thecell monitors are connected through a data line arrangement to amicrocontroller of the two-voltage battery, and wherein at least onevoltage level adapter is provided between at least individual cellmonitors and the microcontroller, which voltage level adapter provides,in the first connection arrangement and in the second connectionarrangement of the battery cell blocks, at an output connected directlyor indirectly to the microcontroller, an output voltage signal that isin a prespecified voltage level interval for an input voltage signalthat is present at an input of the voltage level adapter associated withthe associated cell monitor and has a different voltage level in thefirst connection arrangement and in the second connection arrangement,the interval width of said voltage level interval being smaller than adifference between the voltage level of the input voltage signal in thefirst connection arrangement and in the second connection arrangement.2. The two-voltage battery according to claim 1, wherein a voltage leveladapter is provided for every cell monitor of a battery cell block thatis not permanently connected to the ground point of the two-voltagebattery.
 3. The two-voltage battery according to claim 1, wherein thedata line arrangement is a network and provides bus data lines forcommunication of the microcontroller with the cell monitors and/orwherein the data line arrangement provides a first line routed to themicrocontroller and a second line routed to the microcontroller, whereina voltage difference between the lines is provided at themicrocontroller for analysis of the output voltage signal.
 4. Thetwo-voltage battery according to claim 1, wherein the cell monitor ofthe first battery cell block is capacitively or galvanically connectedto the microcontroller through the data line arrangement.
 5. Thetwo-voltage battery according to claim 1, wherein a transmitter withinductive decoupling is provided as a voltage level adapter, wherein thetransmitter has a microcontroller winding that is connected directly orindirectly to the microcontroller and a cell monitor winding thatinteracts with the cell monitor.
 6. The two-voltage battery according toclaim 5, wherein a transformer is provided as the transmitter.
 7. Thetwo-voltage battery according to claim 5, wherein one common transmitteris provided at least for the plurality of cell monitors, wherein thecommon transmitter has a plurality of cell monitor windings, whereineach cell monitor interacts with at least one cell monitor winding, andwherein one common microcontroller winding is provided for at least twocell monitor windings.
 8. The two-voltage battery according to claim 1,wherein a level converter circuit with galvanic coupling is provided asa voltage level adapter, which circuit is arranged between two adjacentbattery cell blocks in the second connection arrangement.
 9. Thetwo-voltage battery according to claim 8, wherein the level convertercircuit provides a first circuit path for signal transmission from thecell monitor to the microcontroller and a second circuit path for signaltransmission from the microcontroller to the cell monitor.
 10. Thetwo-voltage battery according to claim 8, wherein the level convertercircuit is an integrated circuit and optionally as a part of theassociated cell monitors or wherein the level converter circuit is adiscrete circuit.
 11. The two-voltage battery according to claim 8,wherein more than two battery cell blocks are connected in series withone another in the second connection arrangement, wherein a levelconverter circuit is provided between every two adjacent battery cellblocks, and wherein all level converter circuits are substantiallyidentical in design.
 12. The two-voltage battery according to claim 8,wherein the microcontroller is connected directly to the first batterycell block through the data line arrangement, and wherein all batterycell blocks that are not permanently connected to the ground point ofthe two-voltage battery are connected indirectly to the microcontrollerthrough the first battery cell block.
 13. The two-voltage batteryaccording to claim 9, wherein a first switching module with at least oneswitching element, with a switching input associated with the switchingelement, and with a signal output is provided in the first voltage pathof the level converter circuit and/or wherein a second switching modulewith at least one switching element, with a switching input associatedwith the switching element, and with a signal output is provided in thesecond voltage path of the level converter circuit, wherein theswitching element is arranged in a first switching state or in a secondswitching state depending on an input switching signal present at theswitching input of the switching element, and wherein in the differentswitching states, at least one resistor of the first switching moduleand/or of the second switching module is connected differently in such amanner that the voltage level at the signal output of the firstswitching module and/or of the second switching module is different inthe first switching state of the switching element from the voltagelevel of the signal output in the second switching state.
 14. Thetwo-voltage battery according to claim 8, wherein with respect to twovoltage terminals of the first switching module and/or with respect totwo voltage terminals of the second switching module, a greater voltagedifference is present at the first switching module and/or at the secondswitching module in the second connection arrangement than in the firstconnection arrangement.
 15. The two-voltage battery according to claim1, wherein the voltage level adapter provides a first output voltagesignal in a first voltage level interval for a first input voltagesignal and provides a second output voltage signal in a different secondvoltage level interval for a different second input voltage signal.